SCP then will ask the password for username on the remote host that already specified, insert the username and press enter. Wait until the transfer finished and your file will be copied to the destination server.
Now, if you transfer a big file, let’s say 20 GB file. You can set SCP to run in background so you don’t need to wait in front of your computer until the transfer finished. Here is how to run SCP in background:

hi, I tried to use scp for copying file which size is 4.2 GB. it was stopped at 4G error: file size exceeded. is that any difference when you transfer it in background? fyi, both of my server using fedora core 4.